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Title: Culturable bacteria associated with Antarctic lichens: affiliation and psychrotolerance
Authors: Selbmann, Laura; Zucconi Galli Fonseca, Laura; Ruisi, Serena; Grube, Martin; Cardinale, Massimo; Onofri, Silvano
Abstract: Antarctic habitats harbour yet unexplored
niches for microbial communities. Among these, lichen symbioses are very long-living and stable microenvironments for bacterial colonization. In this work, we present a first assessment of the culturable fraction of bacteria associated
with Antarctic lichens. A phylogenetic analysis based on 16S rRNA gene sequence of 30 bacterial strains isolated from five epilithic lichens belonging to four species(Lecanora fuscobrunnea, Umbilicaria decussata, Usnea
antarctica, Xanthoria elegans) shows that these represent the main bacterial lineages Actinobacteria, Firmicutes,
Proteobacteria and Deinococcus-Thermus. Within the Actinomycetales, two strains group in the genera Arthrobacter and Knoellia, respectively. Most of the other Actinobacteria
form well-supported groups, but could be assigned with certainty only at the family level, and one is in isolated position in the Mycobacteriaceae. The strains in Firmicutes and Proteobacteria belong to the genera Paenibacillus,
Bacillus and Pseudomonas, which were already reported from lichen thalli. Some genera such as Burkholderia and Azotobacter, reported in the literature as also associated
with lichens, have not been detected in this study. One strain represents the first record of Deinococcus in epilithic lichens; it is related to the species Deinococcus alpinitundrae
from Alpine environments and may represent a new
species. Further separated and well-supported clades indicate the presence of possibly new entities. Some of the examined strains are related to known psychrophilic
bacteria isolated from ice and other extreme environments, others with bacteria distributed worldwide even in temperate
climates. Most of the strains tested were able to grow at low temperatures, but tolerated a wider range of temperature.
Ecological and evolutionary implications of these
lichen-associated bacteria are discussed.
Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com/Thu, 31 Dec 2009 23:00:00 GMThttp://hdl.handle.net/2067/14712009-12-31T23:00:00Z